[dav-id]

In my personal experience with working in .NET MVC within VS 2012 it is noticeably slower working with Debug always on as you cannot simply build and refresh the code, each time you need to load the debugger, test drop out of debug, fix, repeat.

I prefer to do as much without debugger and then when I need to inspect variables and step through code drop into debug mode.

With Python this may be different but I doubt it. I expect you will have to wait while the debugger loads up. If you can edit code whilst debugger is running then I can see that being a big plus and a reason to keep it on.